1. Field of the Invention
The present invention relates generally to a motor, and more particularly to a winding cooling structure of shaft motor.
2. Description of the Related Art
In operation, a motor will generate heat to cause rise of temperature of the motor. In case the motor is under a high-temperature condition for a long time, the windings are likely to damage due to overheating. Also, the permanent magnet will be demagnetized to deteriorate the performance of the motor. In order to avoid overheating of the motor, after powered on, the heat generated by the windings is often dissipated by way of conduction or convection. Various heat dissipation structures have been disclosed for dissipating the heat generated by the windings.
FIG. 1 shows a conventional shaft motor, which dissipates the heat by way of natural convection. The housing 1 of the mover of the shaft motor is formed with multiple heat dissipation passages 2 for airflow. When the mover reciprocally moves, the air continuously flows within the heat dissipation passages to dissipate the heat by way of natural convection.
In the above shaft motor, the heat is dissipated by natural intake of air. The heat dissipation effect achieved by such means is limited. Therefore, FIG. 2 shows an improved shaft motor, which dissipates the heat by way of forced convection. As shown in FIG. 2, external high-pressure air is conducted into the gap 5 between the tubular mover 3 and the shaft stator 4 of the shaft motor so as to enhance the heat dissipation effect.
Furthermore, the heat conductivity of air is lower so that water with higher heat conductivity can be selected as a cooling fluid to dissipate the heat by way of convection. FIG. 3 shows a conventional water-cooled shaft motor. A hollow annular section 6 is sandwiched between the tubular mover and shaft stator of the shaft motor. The water flows within the interior space of the annular section 6 to provide a higher heat dissipation effect.
The above conventional techniques are applied to the shaft motor to enhance the convection and heat conduction and dissipation effect. However, as shown in FIG. 1, the air simply flows through the surrounding of the tubular windings to conduct heat to the housing byway of natural convection for dissipating the heat. Also, as shown in FIGS. 2 and 3, only the inner circumference of the tubular windings serves to provide a heat dissipation path. All the above conventional techniques can only achieve limited heat dissipation effect so that the heat generated by the windings as the main heat source can be hardly fully dissipated.